In the past, a valve used in a line for transporting various types of chemicals, pure water, electrolytes, or other fluids, as shown in FIG. 15, has been structured to include a valve body 67 and a drive part 68 connected by metal bolts 69 (for example, see Japanese Unexamined Patent Publication No. 8-159307 and Japanese Unexamined Patent Publication No. 11-304030).
In a conventional valve, there has been the problem that corrosive fluid leaking from or passing through the clearances between the valve body 67 and the drive part 68 or the corrosive gas included in the atmosphere in which the valve is placed has corroded the metal bolts 69 and, in the worst case, has led to the breakage of the metal bolts 69 and the destruction of the valve. As means to solve this problem, the method of giving the metal bolts 69 a corrosion resistant coating or the method of changing the metal bolts 69 to plastic have been attempted. However, with the former method, in particular it is difficult to completely coat the parts engaging with the nuts and the costs greatly increase. Further, with the latter method, as plastic bolts do not have sufficient strength, there was the problem that the range of pressure of the fluid which can be used is limited.